While nuclear weapons were conceived to end a war, in the aftermath of their operational use at Hiroshima and Nagasaki, they became the central (and controversial) means to prevent a war. Nuclear deterrence formed the foundation of U.S. Cold War doctrine and the basis of an extended security guarantee to our allies. But the Cold War ended one-quarter century ago, and questions about the efficacy of deterrence, the need for nuclear weapons, and the ethics surrounding them have resurfaced as some call for further major reductions in inventory or the complete elimination of the U.S. nuclear arsenal. Discussed from the perspective of a military practitioner, this essay highlights the continuing need for U.S. nuclear weapons in a global security environment that is highly complex and uncertain, and describes the means by which the credibility of the nuclear portion of the strategic deterrent is being preserved even as the role and prominence of these weapons have been reduced.